Starter drive for automobile engines or the like



Oct. 13, 19 36. w. O ROSE 2,057,633

STARTER DRIVE FOR AUTOMOBILE ENGINES OR THE LIKE Filed June 15, 1935 INVENTOR.

ATTORNEY.

Patented Oct. 13, 1936 UNITED STATES PATENT OFFICE STARTER DRIVE FOR AUTOMOBILE ENGINES OR THE LIKE Application June 15, 1935, Serial No. 26,761

Claims.

The present invention pertains to a novel .starter drive for automobile engines or the like, particularly the electrically operated mechanical starter for the gasoline motor in an automobile,

5 truck or tractor. The device is also useful in connection with stationary and other engines .that must be turned over in starting.

The general object of the invention is to eliminate some of the defects of the conventional or Bendix starter and to improve the operation of the starter in other'respects. In the conventional starter, the starter gear travels on a threaded sleeve towards the fly wheel gear. In order to prevent travel of the gear along the sleeve under vibration, the gear has a weight fixed thereto, usually in the form of a segment of metal unbalanced with respect to the center of rotation. This weight also determines the rest or idle position of the starter gear. The gear 5 also has a drag pin engaging the threaded sleeve for further resisting movement of the gear under vibration.

One of the difliculties with the conventional starter is that the electric starting motor, and @1 hence the starter gear, acquires a high speed by the time the starter gear meshes with the fly wheel gear, thereby imposing a high torque and strain on the starter assembly as the gears come into mesh. This high speed is developed while the starter gear travels along a rather long threaded sleeve which is given extra length to permit the starter gear to travel a given distance until its off-center weight comes to the bottom position, without the gear interfering with the fly wheel gear.

This objection and others incidental thereto, which will be described below, is overcome in the present invention by means of a free or I floating weight, rather than a fixed weight, associated with the starter gear. According to the invention, the starter gear is formed with a chamber containing a mobile weight such as mercury adapted to find its bottom position by a movement independent of that of the starter gear itself. Consequently, the weight comes to its bottom position without necessitating travel of the starter gear along the threaded sleeve, and the sleeve may therefore be shortened to the extent ordinarily allowed for travelunder the influence of the usual fixed weight. The speed of the starter gear at the time of mesh with the fly wheel gear is correspondingly reduced, and the strains incidental to high speed .1552 meshing are also reduced. The previously mentioned chamber is preferably formed'with a baflle that prevents splashing of the mercury.

Another characteristic of the invention is the provision of a tension spring in place of the usual torsion spring. The latter places certain 5 parts of the assembly under strains which are avoided by the use of a compression spring.

In connection with the compression spring, the starter gear is limited in its movement towards the fly wheel gear by a rotatable stop rather 10 than the usual fixed stop. On engaging the rotatable stop, the starter gear is free to continue in rotation even though the fly wheel gear has not yet moved. In this interval, the rotating starter gear cannot advance further on its 15 threaded sleeve and consequently moves the sleeve back on its shaft, thereby compressing the spring to a pressure corresponding to the load in and on the motor up to the time of turning over. 20

The invention is fully disclosed by way of example in the following description and in the accompanying drawing in which Figure 1 is a side elevation of the device;

Figure 2 is a section on the line 2-2 of Figure 1;

Figure 3 is a section on the line 33 of Figure 2, and

Figure 4 is an elevation of the baflle ring.

Reference to these views will now be made by 30 use of like characters which are employed to designate corresponding parts throughout.

The numeral I designates the starter drive shaft which is usually a prolongation of the shaft of the electric starting motor. The shaft carries a threaded sleeve 2, the forward end of which abuts a taper roller bearing 3 on the shaft I.

- At' the rear end of the sleeve 2 is formed a housing 4 spaced from the shaft I and having one .or more outwardly extending lugs 5. Adjacent 40 to the member 4 is another housing 6 having its wall spaced from the shaft I and formed with -a boss I journaled on the shaft and secured thereto by a key 8. A split ring 9 is fitted in grooves I 0 formed in the shaft I and. boss I. to prevent the member 6 from shifting length- .wise on the shaft, while the key 8 causes the ingthe ears 5. Within the housings 4 and 6 is mounted a coil spring I2 surrounding the shaft Iand having its ends bearing against these parts. This is the main or take-up spring of the device and replaces the torsion spring of the bearing 3.

. sleeve 2 in the usual manner,

conventional starter drive. Obviously, the spring I2 is positioned before assembling the housing 6 and looking it on the shaft.

The starter gear I3 is mounted on the threaded sleeve 2 and has internal threads I4 meshing with those of the sleeve. The rear end of the gear I3 has its diameter enlarged as indicated by the numeral I5, and at this end is formed an annular cavity I6 which is sealed by a flat ring I'I suitably secured in the enlarged end of the gear. The cavity or chamber I6 contains a mobile balanced weight consisting preferably'of aquantity of mercury I8 or any other suitable substance, as distinguished from the usual fixed weight in the form of an enlarged segment on the gear. To prevent excessive splashing and whirling of the mercury in the operation of the device, a bafile ring is fitted in the chamber [6 as shown in Figures 2, 3 and 4. This member is in the nature of a polygonhaving its vertices I9 engaging the outer wallof the chamber and its sides concaved towards the inner wall of the chamber as indicated by the numeral 20.. The pockets: thus formed between the sides of the polygon and the outer wall of the chamber I6 are placed in communication with one another by means of ports ZIformed in the vertices without establishing communication to the interior of the polygon. The mercury is of course contained in the outer pockets as shown in Figures 2 and 3. On the forward end of the housing 4 is slidably mounted a gear retaining sleeve 22 engaging the ring I'I when the starter gear I3 is in the retracted position. The sleeve 22 has an internal shoulder 23 which at this time bears against a stop ring 24 fitted in the wall of the housing 4. The exposed outer wall of the housing 4 is surrounded by a cushion spring 25 bearing against the rear end of sleeve 22 and a shoulder 26 on the rear end of the housing 4.. This spring is considerably lighter than the take-up spring [2 and is under compression to hold the sleeve 22 againstthe gear I3 for a purpose presently to be described.

In the operation of the. device, the shaft I is turned by an electric motor, whereupon the housings .16 and t are also turned, together with the threaded sleeve 2, whereby the starter gear I3 is advanced on the sleeve in the usual manner. It has been observed in actual operation that the gear I3 is so well balanced by the mobile weight I8 therein that it does not rotate while advancing on the threaded sleeve 2. The forward movement of the starter gear is limited by the engagement of a. stop shoulder 21 on its forward end with the outer race 28 of the taper roller At this time the starter gear I3 comes into mesh with the fly wheel gear in the usual manner, and as the shaft I continues. in rotation, it turns the gear I3 and with it the flywheel gear to turn the motor over. Inasmuch as the gear I3 turns freely against the bearing 3 but can now no longer advance on the threaded sleeve 2, the

sleeve must slide back on the shaft I, thereby compressing the take-up spring I2 against the non-rotating housing 6. The final compression of the spring I2 varies according to the work necessary in turning over the motor or, in other words, the load on and in the motor.

When the motor begins to fire, the fly wheel gear speed exceeds that of the starter gear I3 and thus throws the gear I3 back on the threaded The ring I I, which may beconsidered a part Qf. thev gear I3, strikes the retaining sleeve 22 and compresses the spring 25 somewhat. The mobile weight I8 comes to its bottom position without necessitating rotation of the gear I3 on the sleeve 2, as a result of which the compressed spring 25 exerts a pressure against the gear I3 through the slidable retaining sleeve 22. This pressure binds the gear I3 against the walls of the threads of the sleeve'2'sufiiciently to resist slipping of the gear under ordinary vibration on a down grade, but not enough to impede movement of the gear in the starting operation previously described.

The previously mentioned balancing of the gear I3 without lengthwise movement, because of the mobile or floating balanced weight, enables the use of a shorter threaded sleeve than usual. Further, the lengthwise pressure exerted by the cushion spring 25 on the gear I3 and against the threads of the sleeve 2 does away with the need of the usual drag pin to resist shifting of the starter gear under vibration. These two characteristics of the invention eliminate excessive high speed of the starting motor and starter gear I3 when coming into mesh with the fly wheel gear,

which excessive speed is common and objection- 1 able, in the conventional starters, although unavoidable, for the reasons already set forth. Moreover, the substitution of a compression spring for the usual torsion spring does away with the strains and breakage that occur at the parts where the torsion spring is anchored.

The stoppage of the starter gear I3 against the bearing raceI23 provides asmoother, more efficient and less destructive action than when this gear strikes against a fixed collar, as in the conventional devices. Further advantages of the present invention are the avoidance of breakage of the main spring on back firing of the motor and sticking oi thestarter gear against the flywheel.

The advantages of the invention may be further summarized as follows:

l. The. starter gear can not be heard when meshing with the flywheel gear because the short sleeve on. which the starter gear travels. does not permit excessive speed of the starting moto and the starter gear prior to meshing.

2. The short sleeve need not have a stop fixed thereto. because of the fact. that the main takeup spring equalizes the. shock of the load and thusthe rolling stop 28, accompanied by movement of the sleeve into the housing 6.. Consequently, the

expansion of the. spring and accompanying move- .ment of the sleeve out of the housing causes retraction of the starter gear on the sleeve.

The end e a ter ear entering he flywheel gear may be angled orotherwise designed according to the requirements of the flywheel gear, to avoid clashing.

5. Splashing of oilon the threaded sleeve. are.

to leaks from the rear bearingsorotherwise, does not retard and has no other effect on the starter gear in entering the flywheel gear, because of the absence of the usual drag pin that retards the starter gear when there is oil or grease on the threaded sleeve.

6. The durability of the device is considerably improved by the absence of any'parts anchored to one another by screws or bolts. -All the parts being in this sense independent of each other,

there is nothing to loosen or break under strain.

7. The avoidance of delay and excessive high speed in the meshing of the starter gear with the flywheel gear, as previously described, removes the general cause of breakage of flywheel teeth. Sticking of a starter is due to binding of the starter gear on broken flywheel teeth, and this difficulty is overcome in the present invention by removing the cause of broken teeth.

Although a specific embodiment of the invention has been illustrated and described, it will be understood that various alterations in the details of construction may be made without departing from the scope of the invention, as indicated by the appended claims.

What I claim is:

1. In a starter of the class described, a starter drive shaft, an externally threaded sleeve slidable thereon, a starter gear threaded on said sleeve, a spring at one end of said sleeve and adapted to be placed under load on turning of said sleeve within said gear during meshing action of said gear, a stop directly on said shaft and engageable by the other end of said sleeve and by said gear for limiting the movement of said sleeve and gear in one direction, and a spring-backed stop at the first named end of said sleeve for limiting movement of said gear in the other or demeshing direction, said gear being engageable with said spring-backed stop while in threaded engagement with said sleeve, whereby said spring-backed stop exerts pressure on said gear towards the first named stop and against the threads of said sleeve.

2. In a starter of the class described, a starter drive shaft, a threaded sleeve slidable thereon, a starter gear threaded on said sleeve, said gear having a chamber therein, a quantity of mercury disposed in said chamber, a baffle in the form of a serrated plate between the inner and outer walls of said chamber and dividing said chamber into pockets, said plate having ports connecting said pockets, a stop for limiting movement of said gear on said sleeve in one direction, and a spring adapted to be placed under load on turning of said sleeve within said gear.

3. In a starter of the class described, a starter drive shaft, a threaded sleeve slidable thereon, a starter gear threaded on said sleeve, a weight carried by said gear, a housing fixed on said shaft, another housing formed on said sleeve between said gear and the fixed housing and having a sliding connection with said fixed housing, a pressure spring within and bearing against said hous ings, and a stop for limiting movement of said gear on said sleeve in one direction.

4. In a starter of the class described, a starter drive shaft, a threaded sleeve slidable thereon, a starter gear threaded on said sleeve, a stop for limiting movement of said gear on said sleeve in one direction, a spring adapted to be placed under load on turning of said sleeve within said gear, a gear retaining sleeve slidably mounted on the first sleeve and positioned to limit movement of said gear in the other direction, and a spring backing said retaining sleeve and adapted to exert spring pressure on said gear towards the first named stop.

5. In a starter of the class described, a starter drive shaft, a threaded sleeve slidable thereon, a starter gear threaded on said sleeve, a housing fixed on said shaft, another housing formed on said sleeve between said gear and the fixed hous ing and having a sliding connection with said fixed housing, a pressure spring within and bearing against said housings, a gear retaining sleeve slidable on the second named housing, and a spring on the last named housing and holding said retaining sleeve under pressure against said starter gear.

WILLIAM C. ROSE. 

